Reflux nephropathy refers to kidney damage or scarring that results from the backward flow of urine. This abnormal flow can lead to injury of the delicate kidney tissues over time. The scarring can impair the kidneys’ ability to filter waste products from the blood.
The Underlying Cause of Reflux Nephropathy
The primary condition that leads to reflux nephropathy is vesicoureteral reflux (VUR). This occurs when the valve mechanism at the junction where the ureter meets the bladder does not close properly. Normally, this valve acts as a one-way gate, preventing urine from returning to the kidneys during bladder filling and urination. When the valve malfunctions, urine can flow backward, creating pressure within the urinary system.
The backflow of urine, particularly when combined with urinary tract infections, causes injury to the kidney tissue. Bacteria from the bladder can be carried up to the kidneys through the refluxing urine, leading to recurring infections and inflammation. This repeated inflammation and pressure contribute to the formation of permanent scars on the kidney. Vesicoureteral reflux is a congenital condition, meaning it is present at birth, and it is most commonly diagnosed in infants and children, though it can persist or be identified in adulthood.
Recognizing the Signs and Symptoms
The presentation of reflux nephropathy can vary depending on the individual’s age. In infants, signs include unexplained fevers, poor feeding habits, irritability, and a failure to thrive, meaning they are not gaining weight or developing as expected.
Children may present with classic urinary tract infection symptoms, such as painful or frequent urination. New-onset bedwetting after a child has been toilet-trained can also be a sign. Some children experience abdominal pain or discomfort in their flank area, which is the side of the body between the ribs and hip. Adults often present with high blood pressure, known as hypertension, a sign of kidney damage. Other indicators in adults may relate to reduced kidney function, such as swelling in the legs or protein in the urine.
The Diagnostic Process
Confirming a diagnosis of reflux nephropathy involves a series of medical tests. An initial urinalysis is often performed to detect a urinary tract infection. Imaging studies are then used to visualize the kidneys and urinary tract.
A renal and bladder ultrasound is a non-invasive imaging test that uses sound waves to create images of the kidneys and bladder. This scan helps assess the size and shape of the kidneys and can reveal any visible scarring or blockages.
The voiding cystourethrogram (VCUG) is a specialized X-ray procedure considered the primary test to confirm urine reflux. During a VCUG, a catheter fills the bladder with a liquid visible on X-rays, allowing doctors to observe if urine flows backward into the ureters and kidneys during urination, and to grade its severity.
A DMSA scan is a nuclear medicine test that uses a small amount of radioactive material injected into the bloodstream. This scan provides detailed images of the kidney tissue, identifying areas of scarring and assessing the functional capacity of each kidney.
Management and Treatment Approaches
The primary goals for managing reflux nephropathy are to prevent future urinary tract infections, protect the kidneys from further scarring, and address any existing complications. The approach to treatment often depends on the severity of the reflux and the patient’s age. For low-grade reflux, active surveillance may be chosen, as the condition can sometimes resolve on its own as the child grows.
Prophylactic antibiotics involve administering a continuous low dose of antibiotics to prevent recurrent urinary tract infections, thereby reducing the risk of kidney damage. For higher-grade reflux or when infections persist despite antibiotic treatment, surgical or endoscopic procedures may be considered. Ureteral reimplantation is a surgical procedure that involves repositioning the ureter to create a more effective valve mechanism at the bladder junction. Endoscopic injection involves placing a bulking agent near the ureteral opening to help the valve close more completely, preventing backward urine flow. Managing complications like high blood pressure is also a part of treatment, often requiring medication to preserve kidney health.